JP4419883B2 - Image recording device - Google Patents

Description

  The present invention relates to an image recording apparatus for recording an image by a recording head in which recording elements are arranged along a direction orthogonal to the one direction while conveying recording paper in a predetermined direction with a driving force of a driving unit. Is.

  Conventionally, in an image recording apparatus, for example, an ink jet printer, a loaded recording sheet (recording sheet) is conveyed at a constant speed in a predetermined direction by a driving force of a conveying roller.

  In this conveying direction, a recording head in which recording elements are arranged in a direction orthogonal to the one direction is disposed.

  When the recording paper reaches the position where the recording head is disposed, this is detected by a paper detection sensor, and recording by the recording head is started with the leading edge detection by this paper detection sensor as a trigger.

  In recording by the recording head, a signal from an encoder provided on the conveyance roller is used as a reference signal. For example, the rise of the encoder pulse signal is used as the recording timing (image data output timing) for each line.

  In other words, the recording paper conveyance speed is synchronized with the recording timing of the recording head, and even if the recording paper conveyance speed changes due to the change in resolution, the recording timing by the recording head follows this, Image recording is possible.

  Incidentally, the detection signal for detecting the leading edge of the recording paper as described above and the reference signal from the encoder are asynchronous.

  For this reason, for example, if the reference signal from the encoder rises immediately before the detection signal is output, the recording timing is delayed until the next rise (less than one cycle).

  On the other hand, if there is a rising edge of the reference signal from the encoder immediately after the detection signal is output, the recording timing is reached without delay.

  For this reason, a deviation corresponding to a maximum of less than one line occurs depending on the timing of the leading edge detection (output of the leading edge detection signal) by the paper detection sensor.

  Such misalignment results in misregistration for each recording sheet when a plurality of copies are recorded, which degrades the finished quality. In particular, when a color image (including a full color image) is printed by multi-pass, a plurality of colors are recorded in an overlapping manner. However, a recording position shift directly causes a color shift, resulting in a deterioration in image quality. .

In order to solve this problem, the first rising edge of the reference clock (for example, a reference clock generated by multiplying the reference signal from the encoder by N) after the output of the leading edge detection signal from the paper detection sensor is detected and detected. It has been proposed to reduce the error to 1 / N of the period of the reference signal by synchronizing the reference signal from the encoder and the detection signal based on the reference clock (see Patent Document 1).
JP 2001-150656 A

  However, since the recording timing signal is newly generated from the reference signal from the encoder in Patent Document 1, it cannot be said that the recording timing signal is faithfully synchronized with the recording sheet conveyance speed, and the error in the recording start timing is reduced. On the other hand, the conveyance state of the recording paper during recording when there is a driving error of the driving means for conveying the recording paper is not taken into consideration.

  In other words, the technique of Patent Document 1 is a technique on the assumption that the recording paper is conveyed at a constant speed with respect to the recording timing during recording, while the error of the recording start position is reduced. In particular, no consideration is given to the most important problem of image quality degradation.

  In consideration of the above facts, the present invention can reliably match the writing position of the image on the recording paper, and also follows the unevenness in the conveyance of the recording paper due to the driving force of the driving means. An object is to obtain an image recording apparatus capable of generating an output timing signal of image data.

The present invention includes a recording head including a recording element. The recording head is opposed to a recording medium transport path that is transported in one direction by a driving force of a driving unit, and the recording head, the recording medium, Is an image recording apparatus that forms an image on the recording medium by detecting the driving state of the driving means that conveys the recording paper, and outputs a driving waveform having periodicity. Operating state detection means, a paper detection sensor for detecting the leading end of the recording paper in the transport direction before the image recording area of the recording paper reaches the recording head, and a processing capability determined by a system clock. and, based on a predetermined output timing with respect to the input image data, and image recording control means for controlling the image recording by the recording element of the recording head, the period of at least the drive waveform Even using the count signal having a period shorter, counting means for counting repeatedly to reset every half cycle of the drive waveform output by the drive state detecting means, the conveyance direction leading edge of the recording sheet by the paper detecting sensor A count value registering unit for registering a count value by the counting unit at the time of detection of a portion, and a timing that coincides with the inversion timing of the count signal immediately after the detection of the leading end portion in the conveyance direction of the recording paper by the paper detection sensor And a timing generation unit that generates a periodic image data output timing signal whose phase is shifted from the drive waveform by the count value registered by the count value registration unit .

  In the above invention, the recording head has a plurality of recording elements arranged over the entire region orthogonal to the conveyance direction of the recording paper, and scans the image recording surface of the recording medium by moving in the direction orthogonal to the recording head. It is an FWA (Full Width Array) type recording head.

  Further, in the image recording apparatus to which the FWA type recording head is applied, the recording medium is circulated so as to repeat scanning of the image recording surface by the recording head a plurality of times, and the image recording is performed by dividing each lap. And a multi-pass mechanism for performing the above.

  Further, in the present invention, the recording head scans the image recording surface of the recording medium by moving in both the direction perpendicular to the conveyance direction of the recording paper and the one direction, and is a PWA (Partial Width Array) type. It is characterized by being a recording head.

  According to the present invention, the FWA type recording head will be described as an example. First, since the period of the driving waveform detected by the driving state detecting means is a period of mechanical operation, generally, the frequency is about 18 KHz. On the other hand, it is a well-known technique that the so-called system clock used in the control system has a frequency of about 40 MHz.

  Therefore, the resolution of one cycle of the drive waveform can be increased by converting the drive waveform into a system clock having a shorter cycle.

  First, the counting means repeatedly counts so as to reset every half cycle of the driving waveform output by the driving state detecting means.

  In this state, when the leading end of the recording paper in the conveyance direction is detected by the paper detection sensor, the immediately following count resolution (one count unit) is used as the starting point of the output timing signal of the image data.

  As a result, even if the drive waveform and the detection signal of the paper detection sensor are not synchronized, the error is within one system clock, so that there is no problem in positional deviation during image recording.

  Next, the output timing signal and the drive waveform are synchronized during image recording, and are counted every ½ period of the drive waveform when the paper detection sensor detects the leading end of the recording paper in the conveyance direction. The registered count value is registered in the count value registration means.

  Based on the registered count value, a continuous output timing signal can be generated by delaying the inversion timing of the output timing signal with respect to the drive waveform.

  Here, when the multi-pass mechanism is provided as the image recording apparatus of the present invention, there is no deviation in the recording position in the relative movement direction between the recording head and the recording paper between each round of image recording. It is possible to prevent the deterioration.

  The above operations and effects are the same even for a PWA type recording head.

  In the present invention, when the driving waveform output from the driving state detecting means is a binary inversion signal, and when the driving waveform is a high level signal, the leading end of the recording paper is detected by the paper detection sensor. The timing immediately after that is synchronized with the system clock as the rise of the output timing signal, and then the count value registered by the count value registering means is delayed from the timing when the drive waveform is inverted to low level or high level. And the output timing signal is inverted.

  Since the drive waveform is a binary inverted signal, the leading edge of the recording paper may be detected when the drive waveform is at a high level.

  In this case, when the leading edge is detected, the timing synchronized with the system clock immediately after that is the rise of the output timing signal, and then the count is started from the timing when the drive waveform is inverted to low level or high level. The output timing signal may be inverted by delaying the count value registered by the value registration means.

  In the present invention, the driving waveform output from the driving state detecting means is a binary inversion signal, and when the driving waveform is a low level signal, the leading end of the recording paper in the conveyance direction is detected by the paper detection sensor. The count value registered by the count value registration means starting from the time when the drive waveform is inverted to the high level or the low level after the time synchronized with the system clock immediately thereafter is the rising edge of the output timing signal. The output timing signal is inverted by delaying by a minute.

  Since the drive waveform is a binary inverted signal, the leading edge of the recording paper may be detected when the drive waveform is at a low level.

  In this case, when the leading edge is detected, the timing synchronized with the system clock immediately after that is the rising edge of the output timing signal, and then the counting is started from the timing when the drive waveform is inverted to high level or low level. The output timing signal may be inverted by delaying the count value registered by the value registration means.

  In the present invention, a plurality of the recording heads are arranged in the conveyance direction of the recording paper, and the paper detection sensors are provided corresponding to the respective recording heads.

  Although the positions of the plurality of recording heads are physically different, basically, a sheet detection sensor may be provided only on the most upstream side in the conveyance direction of the recording medium. However, in order to eliminate an assembly error or the like of each recording head, it is preferable to provide a sheet detection sensor corresponding to each recording head.

  As described above, according to the present invention, the image writing position on the recording paper can be surely matched, and the recording paper conveyance unevenness due to the driving force of the driving means can be followed, and the image for each line can be obtained. This has an excellent effect that a data output timing signal can be generated.

(First embodiment)
FIG. 1 shows a schematic configuration diagram of an FWA (Full Width Array) type ink jet printer 10 as an image recording apparatus according to the first embodiment.

  In the center of the apparatus, a conveyor belt 12 that circulates along a predetermined locus is wound around a plurality of (four in the first embodiment) rollers 14, 16, and 18.

  A part of the rollers 14, 16, 18 includes a driving roller that rotates by receiving a driving force of a driving unit (not shown), and the driving belt 12 causes the conveyor belt 12 to move to the arrow A in FIG. 1. Circulate in the direction.

  A pulse encoder 19 is attached to one of the three rollers 14, 16, 18 (for example, the roller 18), and a pulse signal (pulse encoder signal) corresponding to the rotation of the roller 16 is generated. It is sent to the recording head controller 100.

  The upper part of the circular locus of the conveyor belt 12 is a substantially horizontal plane, and the conveyor belt 12 is linearly conveyed. This pulse encoder signal is applied as a so-called print clock signal and serves as a reference for the timing of image recording for each color.

  A head unit 37 composed of a plurality of recording heads 36 whose driving is controlled by the recording head controller 100 is disposed along the conveying direction above the conveying belt 12 that is linearly conveyed.

  The recording head 36 is used for discharging reaction liquid, discharging C color ink, discharging Y color ink, discharging M color ink, and discharging K color ink in order from the upstream side in the transport direction.

  In each recording head 36, nozzles 40 (see FIG. 2) to be described later are arranged over the entire region (main scanning direction) orthogonal to the conveying direction of the conveying belt 12.

  A paper feed tray 20 is disposed on the lower left side of the transport belt 12 in FIG. A plurality of recording papers P are stacked on the paper feed tray 20.

  A paper feed conveyance path 22 is provided between the paper feed tray 20 and a position where the conveyance belt 12 is wound around the leftmost roller 14.

  The uppermost recording paper P is taken out from the paper feed tray 20, and the taken-out recording paper P is guided to the paper feeding / conveying path 22, and the recording head for the reaction liquid on the uppermost stream side. It is sent out onto the conveyor belt 12 from the upstream side of the arrangement position of 36.

  The conveyance belt 12 has a function of closely holding the recording paper P, and the recording paper P that is in close contact with the conveyance belt 12 is supplied with reaction liquid, C color ink, Y color ink, Liquid droplets are ejected in the order of M color ink and K color ink, and a full color image is formed.

  The reaction liquid has a function of promoting the permeability of the recording paper P of each color ink of CMYK, and is a so-called pre-processing in which droplet discharge is performed on all print dots regardless of image data. Although it is positioned, it is not essential for image formation.

  Each recording head 36 corresponds to an ink cartridge (not shown), and an appropriate amount of ink or reaction liquid (hereinafter collectively referred to as “ink or the like” if necessary) is an ink tank 41 ( (See FIG. 2).

  Each recording head 36 is driven in synchronization with a print start signal (timing signal) from the recording head controller 100, and ink droplets of each color are ejected based on image data.

  Further, a scraper 26 is provided corresponding to the roller 16 positioned at the right end of the transport belt 12, and the recording paper P on which image recording has been completed is peeled off from the transport belt 12, and the paper discharge tray 30 is disposed via the discharge path 28. It is structured to send out to

  As shown in FIG. 2, the recording head 36 includes an ink tank 41, a supply path 44, a pressure chamber 46, a nozzle 40, and a piezoelectric element 42.

  The ink tank 41 stores ink and the like from an ink cartridge (not shown). The ink tank 41 communicates with a pressure chamber 46 via a supply path 44, and the pressure chamber 46 is externally connected via a nozzle 40. Communicated with.

  A part of the wall surface (the lower surface in FIG. 2) of the pressure chamber 46 is made of a vibration plate 46A. A piezoelectric element 42 is attached to the vibration plate 46A, and the vibration plate 46A is vibrated by the piezoelectric element 42. A pressure wave is generated in the ink in the chamber 46. That is, ink or the like stored in the ink tank 41 is ejected from the nozzle 40 via the supply path 44 and the pressure chamber 46 by a pressure wave generated by vibration of the piezoelectric element 42.

  By the way, in the first embodiment, the timing of starting image recording on the recording paper P is the first timing signal after the leading edge of the recording paper P is detected by the paper detection sensor 32 provided on the most upstream side of the head unit 37. The rise time is. In this case, the detection timing of the leading edge of the recording paper 32 by the paper detection sensor 32 varies depending on the loading state of the recording paper 32, and a timing signal generated based on the output waveform from the pulse encoder 19 provided on the conveying roller 18. Are out of sync.

  For this reason, conventionally, the timing signal rises immediately before the leading edge of the recording paper P is detected by the paper detection sensor 32, and the timing signal rises immediately after the timing signal rises less than one line. The recording start position may be shifted.

  Therefore, in the first embodiment, a count value using the system clock is applied based on the output waveform from the pulse encoder 19, so that a fixed value after the leading edge of the recording paper P is detected by the paper detection sensor 32. The timing of the first rising edge of the timing signal has come.

  FIG. 3 is a block diagram functionally showing control for generating an image recording timing signal in the recording head controller 100.

  The pulse encoder 19 and the paper detection sensor 32 are connected to the increment counter 104 via the activation determination unit 102. The increment counter 104 is connected to a clock generator 106 that generates a count clock serving as a count unit applied to the first embodiment based on a system clock (40 MHz).

  The increment counter 104 has a function of counting the count clock, is a time when the paper is not detected by the paper detection sensor 32, and is counted every time the pulse signal from the pulse encoder 19 is inverted. The value is reset and started.

  The sheet detection sensor 32 is connected to the count value storage unit 108 and the timing signal generation unit 110.

  The count value storage unit 108 reads and stores the count value m at that time from the increment counter 104 with the edge (rising or falling) of the paper presence signal as a trigger.

  This m value is a count value from the edge (rising or falling) of the pulse encoder signal until the leading edge of the recording paper P is detected.

  In addition, the timing signal generation unit 110 executes the initial rise of the timing signal (signal inversion) in synchronization with the count interval immediately after the edge of the paper presence signal by the paper detection sensor 32 as a trigger.

  Further, the pulse encoder 19 to the pulse encoder are provided on the condition that a paper detection signal from the paper detection sensor 32 (a signal that is maintained at a high level or a low level while detecting paper) is input to the timing signal generation unit 110. When an edge (inversion time) of the signal is detected, an instruction signal for starting the countdown is output to the countdown start instructing unit 112. Thereby, the countdown start instructing unit 112 is activated.

  The countdown start instructing unit 112 is connected to the count value reading unit 114 and, when activated by the countdown start instruction, controls the count value reading unit 114 to read the count value stored in the count value storage unit 108. To do.

  The read count value is set in the decrement counter 116, and countdown is started. The decrement counter 116 also receives a clock pulse from the clock generator 106, and counts down (decrement) at the same count timing (same frequency) as the increment counter 104.

  In addition, although the increment counter 104 and the decrement counter 116 are configured separately, a single up / down counter may be used.

  When the count value becomes “0” by the countdown by the decrement counter 116, a countdown end signal is sent to the timing signal generator 110.

  Each time the countdown end signal is input, the timing signal generator 110 inverts the timing signal.

  Further, while the signal from the paper detection sensor 32 (paper presence signal) is being output, the instruction signal for starting the countdown is repeatedly output every time the pulse encoder signal is inverted.

  By repeating the above, the timing signal generation unit 110 generates a timing signal having the same cycle as the pulse encoder signal and having a predetermined phase difference (for the stored count value), and outputs it via the timing signal output unit 118. Is done.

  The operation of the first embodiment will be described below.

  When printing is instructed, the recording paper P fed one by one from the paper feed tray 20 is brought into close contact with the transport belt 12 and transported in the sub-scanning direction at a predetermined pitch or continuously at a constant speed, and the recording head 36 Ink droplets are selectively ejected from the nozzles 40 to the recording paper P based on the image data.

  Ink ejection is controlled by a drive signal of the piezoelectric element 42 based on the image data. This drive signal is a continuous trapezoidal wave and is output at a period of 14 μsec to vibrate the piezoelectric element. This vibration is transmitted to the vibration plate 46A of the pressure chamber 46, and the vibration plate 46A vibrates to generate a pressure wave in the ink in the pressure chamber 46. By this pressure wave, the ink stored in the ink tank 41 is ejected from the nozzle 40 through the supply path 44 and the pressure chamber 46.

  When the recording of the entire image based on the image data is completed on the recording paper P, the recording paper P is peeled off from the transport belt 12 by the scraper 26 provided corresponding to the roller 16 positioned at the right end of the transport belt 12, It is sent out to the paper discharge tray 30 via the discharge path 28.

  Here, in order to synchronize with the output timing of image data when an image is recorded on the recording paper P, the recording head controller 100 generates a timing signal for starting printing.

  The timing signal generation procedure will be described below with reference to the timing chart of FIG.

  The pulse encoder signal outputs a high level / low level repeated inversion signal in accordance with the driving of the conveyor belt 12.

  Here, the increment counter 104 is reset / started at each edge (rising or falling) of the pulse encoder signal in the non-detection (high level) state of the recording paper P by the paper detection sensor 32, and based on the clock pulse. Count up.

  At this time, if the recording paper P is detected by the paper detection sensor 32 (falling edge from high level to low level), the count value storage unit 108 reads and stores the current count value m. In the first embodiment, the time when the recording paper P is detected is the high level time of the pulse encoder 19.

  In synchronism with this (precisely, the count immediately after), the timing signal for starting printing is inverted from the low level to the high level.

  Here, since the conveying belt 12 continues to be driven, when the predetermined time t1 elapses, it becomes the next edge of the pulse encoder signal (falling in the first embodiment). Using the inversion timing of the pulse encoder signal as a trigger, the decrement counter 116 counts down in synchronization with the clock pulse with the stored count value m as the maximum value.

  When the countdown ends, the timing signal is inverted at this point, and the countdown is started again after waiting for the edge of the next pulse encoder signal.

  By repeating the above, a timing signal having a predetermined cycle can be generated.

  The time t2 that ends after the countdown is started becomes a half cycle of the pulse encoder signal by adding the predetermined time t1. In other words, the timing signal is a signal having the same period (frequency) that is out of phase by the time counted by the increment counter 104 with respect to the pulse encoder signal.

  As a result, a timing signal can be generated at a timing based on the conveyance state of the conveyance belt 12, and the maximum of one clock of the system clock regardless of the detection timing of the leading edge of the recording sheet P by the sheet detection sensor 32. Since only an error occurs, no image recording position shift occurs between the recording sheets.

  In the first embodiment, the timing when the leading edge of the recording paper P is detected by the paper detection sensor 32 is described as being high level of the pulse encoder signal. However, when the pulse encoder signal is low level, the recording paper P is detected. As shown in FIG. 5, the timing signal is generated by the same control as long as the timing signal is raised at the count break immediately after the leading edge of the recording paper P is detected as shown in FIG. Can do.

  As described above, in the first embodiment, the pulse encoder signal and the timing signal for image recording are not synchronized, and the maximum pulse encoder of the maximum pulse encoder caused by the leading edge detection time of the recording paper P is not used. Recognizing the leading edge detection time of the recording paper P with a count value having a period equivalent to a system clock whose cycle is extremely short with respect to the cycle of the pulse encoder signal with a deviation of less than one cycle, and using this count value, the pulse encoder By synchronizing the signal and the timing signal with a predetermined phase difference, it is possible to improve the relative accuracy of image recording relative position between the recording sheets P.

  In the first embodiment, the inkjet printer 10 has been described as an example, but the same effect can be obtained even with an image recording apparatus using an LED array.

  In particular, when multi-pass printing is performed by opening the scraper 26 and keeping the recording paper P in close contact with the conveying belt 12, the recording position does not shift in each printing pass. Therefore, the image quality is not deteriorated due to color misregistration, and the effect of the present invention is great.

(Second Embodiment)
The second embodiment of the present invention will be described below. In addition, about the same component as 1st Embodiment, the same code | symbol is attached | subjected and description of the structure is abbreviate | omitted.

  As shown in FIG. 6, the image recording apparatus 10 </ b> A according to the second embodiment is upstream of the recording head 36 in the recording sheet conveyance direction with respect to the image recording apparatus 10 shown in the first embodiment. A dedicated paper detection sensor 32 is arranged in the vicinity.

  Each recording head 36 starts printing with the detection of the leading edge of the recording paper P by each paper detection sensor 32 as a trigger.

  Since the distance between the paper detection sensor 32 and the corresponding recording head 36 is short, the driving error of the driving means for transporting the recording paper P is reduced, and higher-precision printing can be realized.

  In particular, the effect on the recording head 36 (for example, a K-color recording head) disposed at a location away from the paper detection sensor 32 in FIG. 1 is great.

(Third embodiment)
The third embodiment of the present invention will be described below. In addition, about the same component as 1st Embodiment, the same code | symbol is attached | subjected and description of the structure is abbreviate | omitted.

  As shown in FIG. 7, the image recording apparatus 10B according to the third embodiment records a driven roller 15 provided with a pulse encoder 19 with respect to the image recording apparatus 10 shown in the first embodiment. It is arranged in the vicinity of the head 36.

  By disposing the pulse encoder 19 in the vicinity of the recording head 36, even if there is a driving error of the driving means for conveying the recording paper P, the conveyance state of the recording paper P can be directly reflected on printing. As a result, it is possible to perform more precise printing following the conveyance state.

(Fourth embodiment)
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIGS.

  FIG. 8 shows a schematic configuration of a PWA inkjet printer 200 according to the fourth embodiment.

  In the third embodiment, the conveyance direction of the recording paper P is the sub-scanning direction (see arrow G in FIG. 8), and the direction orthogonal to the sub-scanning direction is the main scanning direction (see arrow F in FIG. 8). And

  The ink jet printer 200 includes a carriage 210 on which black, yellow, magenta, and cyan ink jet recording heads 36 are mounted.

  A pair of brackets 212 project from the upstream side of the carriage 210 in the conveyance direction of the recording paper P, and a circular opening is formed in the bracket 212 and is laid in the main scanning direction. Is inserted.

  A driving pulley 216 and a driven pulley 218 are disposed at both ends in the main scanning direction. A timing belt 220 is wound around the driving pulley 216 and the driven pulley 218, and the carriage 210 is fixed to a part of the timing belt 220. Thereby, the carriage 210 can reciprocate in the main scanning direction.

  The ink jet printer 200 is provided with a sub-scanning mechanism including a conveyance roller 222 and a discharge roller 224. This sub-scanning mechanism performs sub-scanning of recording paper P fed one by one from a paper feed tray 226 that stores recording paper P before printing (printing) in a bundle at a predetermined pitch or continuously at a constant speed. Transport in the direction.

  As shown in FIG. 9, a maintenance unit 202 is disposed at the right end of FIG. 9 in the moving direction of the recording head 36 so that the recording head 36 can be maintained.

  A code film 204 is disposed in the vicinity of the shaft 214, and the encoder 206 detects a code on the code film 204 to generate a print clock signal.

  In addition, a paper detection sensor 32 is disposed in the vicinity of the recording head 36 so that the presence or absence of the recording paper P can be detected.

  Since the printing operation using the output signal of the paper detection sensor 32 and the output signal of the encoder 206 is the same as the printing operation described in detail in the first embodiment, the description of the operation is omitted.

  As described above, the present invention can be applied not only to the FWA type ink jet printer but also to the PWA type ink jet printer, and the FWA type ink jet print can obtain the same effect.

1 is a schematic configuration diagram of an FWA type inkjet printer according to a first embodiment. FIG. 2 is a cross-sectional view showing an internal structure of a recording head. FIG. 3 is a block diagram functionally illustrating control for generating an image recording timing signal in a recording head controller. 6 is a timing chart for generating a timing signal when the leading edge of a recording sheet is detected when the pulse encoder is at a high level. 6 is a timing chart for generating a timing signal when the leading edge of a recording sheet is detected when the pulse encoder is at a low level. It is a schematic block diagram of the image recording device which concerns on the 2nd Embodiment of this invention. It is a schematic block diagram of the image recording device which concerns on the 3rd Embodiment of this invention. It is a perspective view which shows the outline of the PWA type inkjet printer which concerns on the 4th Embodiment of this invention. FIG. 9 is a front view showing in detail the recording head of the PWA inkjet printer shown in FIG. 8 and the surrounding image recording portion.

Explanation of symbols

P Recording paper 10 FWA type inkjet printer (image recording device)
12 Conveying belt 14, 16, 18 Roller 19 Pulse encoder (driving state detecting means)
32 Paper detection sensor 36 Recording head 37 Head unit 40 Nozzle 100 Recording head controller (image recording control means)
102 Start determination unit 104 Increment counter (counting means)
106 clock generation unit 108 count value storage unit (count value registration means)
110 Timing signal generator (timing generator)
112 Countdown start instructing section 114 Count value reading section 116 Decrement counter (timing generating means)
118 Timing Signal Output Unit 200 PWA Inkjet Printer 202 Maintenance Unit 204 Code Film 206 Encoder 210 Carriage 212 Bracket 214 Shaft 216 Drive Pulley 218 Followed Pulley 220 Timing Belt 222 Conveying Roller 222
224 discharge roller 226 paper feed tray

Claims (7)

A recording head including a recording element, and the recording head is opposed to a recording medium transport path that is transported in one direction by a driving force of a driving unit, so that the recording head and the recording medium are relatively An image recording apparatus for forming an image on the recording medium by moving the image recording apparatus,
A driving state detecting unit that detects a driving state of the driving unit that conveys the recording paper and outputs a driving waveform having periodicity;
A paper detection sensor for detecting a front end of the recording paper in the transport direction before the image recording area of the recording paper reaches the recording head;
An image recording control unit that operates under a processing capability determined by a system clock and controls image recording by the recording element of the recording head based on a predetermined output timing with respect to input image data;
Counting means for repeatedly counting so as to reset every half cycle of the drive waveform output by the drive state detection means, using a count signal having a cycle shorter than at least the cycle of the drive waveform;
A count value registration means for registering a count value by the counting means at the time of detection of the leading end of the recording paper in the transport direction by the paper detection sensor;
The timing coincident with the inversion timing of the count signal immediately after detection of the leading edge of the recording paper in the conveyance direction of the recording paper by the paper detection sensor is set as the rising or falling start point, and the drive waveform is counted by the count value registered by the count value registration means. A timing generation means for generating a periodic image data output timing signal out of phase with respect to
An image recording apparatus.   The recording head is an FWA (Full Width Array) type recording head in which a plurality of recording elements are arranged over a length equal to or greater than the width of the recording paper in a direction orthogonal to the conveyance direction of the recording paper. The image recording apparatus according to claim 1, wherein:   The image recording apparatus according to claim 2, further comprising: a multipath mechanism that circulates the recording medium so as to repeat scanning of the image recording surface by the recording head a plurality of times, and divides the recording medium in each lap to execute image recording. .   A PWA (Partial) that scans an image recording surface of a recording medium by moving the recording head relative to the recording sheet in both the direction orthogonal to the conveyance direction of the recording sheet and the one direction. 2. The image recording apparatus according to claim 1, wherein the image recording apparatus is a (Width Array) type recording head.   Immediately after the driving waveform output by the driving state detecting means is a binary inversion signal, and when the driving waveform is a high-level signal, the paper detection sensor detects the leading edge of the recording paper conveyance direction. The timing synchronized with the system clock is set to the rise of the output timing signal, and then the output is delayed by the count value registered by the count value registration means starting from the timing when the drive waveform is inverted to low level or high level, and the output The image recording apparatus according to claim 1, wherein the timing signal is inverted.   Immediately after the drive waveform output by the drive state detection means is a binary inversion signal, and when the drive waveform is a low level signal, the paper detection sensor detects the leading edge of the recording paper conveyance direction. The timing synchronized with the system clock is set to the rise of the output timing signal, and then the output is delayed by the count value registered by the count value registration means starting from the timing when the drive waveform is inverted to the high level or the low level, and the output The image recording apparatus according to claim 1, wherein the timing signal is inverted.   7. A plurality of the recording heads are arranged in the conveyance direction of the recording paper, and the paper detection sensors are provided corresponding to the respective recording heads. The image recording apparatus according to any one of the above.

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